There have been conventionally provided power converter apparatuses (parallel driven devices) in which a plurality of power converter circuits are connected in parallel and driven in parallel to each other, based on the same AC voltage, the power converter circuits using a plurality of power semiconductor devices to conduct pulse width modulation control. However, when a plurality of power semiconductor devices are connected in parallel to each other, a characteristic variation in manufacturing a power semiconductor device causes an unbalance in currents flowing through the power semiconductor devices. Accordingly, due to a characteristic variation, switching at the same timing causes an uneven current flow in a power semiconductor device turning on early and a power semiconductor device turning off later, and this leads to a large switching loss for generating heat. Since for suppressing the heat generation, a large-sized heat dissipation fin is required, it is difficult to downsize a parallel driven device. Further, when a current deviation becomes larger to exceed a rated current of a power semiconductor device, a failure might develop to invite such a problem that even parallel driving of the power semiconductor devices cannot increase an output current.
For example, Patent Document 1 discloses a PWM-type parallel driven device which enables suppression of such a current unbalance. In addition, the parallel driven device includes a correction circuit capable of independently delaying a rise and a fall of a PWM waveform. In this case, the correction circuit proportionally integrates a difference between output currents of the respective parallel driven devices to determine a deviation of output currents, and conducts control such that at the rise of a PWM waveform, a rise delay time of a correction circuit of the parallel driven device having a large output current is longer than a delay time of a correction circuit of the parallel driven device having a small output current, and conducts control such that at a fall of the PWM waveform, a fall delay time of the correction circuit of the parallel driven device having a large output current is shorter than a delay time of the correction circuit of the parallel driven device having a small output current.